JPH02246486A - Method for transmitting still picture utilizing public line - Google Patents

Abstract

PURPOSE:To transmit and receive both a color still picture and a black/white standard system still picture by converting a black/while picture signal into a television telephone signal with a digital signal processing unit in a MODEM for facsimile application. CONSTITUTION:A memory of a digital signal processing unit of a facsimile MODEM 2 is provided with a program/data area 201 for processing a facsimile signal and a program/data area to execute the AM-PM modulation of a black/ white picture. When the signal of the color picture is received, a color still picture data is generated according to the software stored in the memory 201. On the other hand, when a black/white picture signal is received, a CPU 3 digitizes AM-PM modulation to generate a picture data according to the software written in the memory area 202, sends the result to a main bus and displayed on a display device. Thus, the color still picture and the black/white still picture are sent and received by using the facsimile transmission system.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a still image transmission method using a public line, and in particular, still image information is transmitted as a facsimile signal, received by a facsimile modem, and transmitted to a television. The present invention relates to a still image transmission method that allows still images to be played back on a telephone.

2. Description of the Related Art A method for transmitting color still images over public telephone lines using a standard modem for facsimile was announced in a preliminary report of the Institute of Image Electronics Engineers of Japan (June 4, 1984). However, this concerns the transmission of color still images only.

The transmission method for black-and-white videophone calls is based on the analog telephone band still image video communication method standardized by the Telegraph and Communication Technology Committee (hereinafter abbreviated as T'I'C), and is Manufacturers have announced products using this method.

This method was recommended by the TTC in 1988 as the standard method for black-and-white videophone calls in Japan.

However, the current TTC standard method for still image videophone calls is
It is a black-and-white image transmission method and is currently the mainstream method for videophone calls. In order to be able to connect to this standard method, a method called Av-pH1 modulation (amplitude-phase change R) is required.
It was necessary to modulate and demodulate and transmit black and white still images. A dedicated IC is manufactured for this TTC standard system.

As mentioned above, either method can only transmit either a color image or a black and white image in a videophone. Therefore, as a method for transmitting both color and monochrome images in a videophone, conventionally, as shown in FIG. 4, a facsimile modem 100 that receives color still images and an Am-
A tp adjuster 101 is provided in parallel via a switch 102.

Problems to be Solved by the Invention As mentioned above, in order to be able to transmit and receive both color still images and black and white standard still images in a videophone, it is necessary to use, for example, the G[II facsimile modem and hardware. It is necessary to use two types of integrated circuit chips for Al1-pfll modulation, and to perform switching in some way, which has the drawback of increasing the amount of hardware in the device.

The present invention can transmit and receive color still images and black and white still images using a facsimile transmission system, does not require an Am-pm modulator, can easily switch between receiving color still images and black and white still images, and requires no hardware. It is an object of the present invention to provide a transmission method that does not cause any increase.

Means for Solving the Problems In order to achieve the above-mentioned objects, the present invention transmits a color still image using a facsimile signal over a public telephone line, and transmits the color still image signal within a modem for facsimile.
In a videophone system that converts the black and white image signal into a videophone signal using the C standard method and displays the color image on the videophone, the digital signal processing device in the facsimile modem converts the black and white image signal into a videophone signal. It is characterized by converting.

As shown in Figure 1, the color or black and white image signal sent from the public telephone line is applied to the facsimile modem 2 via the network control unit NCUJ, and its output is
Sent to PU3.

In this invention, the Apm modulation circuit used in the prior art is not used.

The memory of the digital signal processing unit (DSP) of the facsimile modem 2 includes a program data area 201 for processing facsimile signals, as shown in FIG.
and a program/data area 202 for executing AOI-1)I11 modulation of a monochrome image.

When a color image signal is received, color still image data is created according to the software stored in the memory area 201.

On the other hand, when a black and white image signal is received, memory area 2
According to the software stored in 02, CPU3
digitizes the Am-pm modulation to create image data, sends it to the main bus 30, and displays it on the display device 210.

Note that there is a third
It is configured as shown in the figure.

Effects of the Invention According to the present invention, the role of the modulation TC, which has conventionally been used in black-and-white videophones, can be performed by a program used in the DSP on the facsimile and modem side. Furthermore, l) The system becomes simpler because no dedicated IC or system changeover switch is required.

2) Since parts that were previously processed by hardware are converted to software, changing and adding functions becomes easier. For example, functions such as transmission error checking can be added to 4'' without any changes to the system hardware.

3) The number of system parts is reduced, improving cost and reliability.

4) By using the color still image videophone system described in the prior art section, it is also possible to connect to the standard system for black and white still image videophones.

There are other advantages as well.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the contents of a memory used in the embodiment of FIG. 1,
FIG. 3 is a circuit diagram showing an example of the connection between the CPU and DSP in the embodiment of FIG. 1, and FIG. 4 is a circuit diagram showing an example of a conventional circuit. 2...Facsimile modulation circuit block 201...
Facsimile modem data area 202...Am-p
m modulation area

Claims (1)

[Claims] (1) Transmit a color still image as a facsimile signal via a public line, convert the color still image signal into a TTC standard videophone signal in the facsimile modem, and send the color image over the videophone. A method for transmitting still images using a public line, in a videophone system for displaying still images, the method comprising converting a black and white image signal into a videophone signal using a digital signal processing device in the facsimile modem.